What tissues, aside from the heart, are commonly affected by atherosclerosis and what are the typical sites for biopsy to confirm diagnosis?

Atherosclerosis Beyond the Heart: Affected Tissues and Diagnostic Biopsy Sites

Atherosclerosis commonly affects multiple vascular beds beyond the heart, with the most common sites being the carotid, renal, mesenteric, and lower extremity arteries, which are typically biopsied when clinically indicated to confirm diagnosis. 1

Common Tissues Affected by Atherosclerosis

Atherosclerosis is a systemic disease that affects various arterial beds throughout the body:

1. Lower Extremity Arteries

• Most commonly affected peripheral site
• Prevalence increases with age (18% in population aged 60-90 years) 1
• Typically affects femoral, popliteal, and tibial arteries
• Manifests as intermittent claudication or critical limb ischemia

2. Carotid Arteries

• High-risk site due to potential for stroke
• Prevalence of significant stenosis (≥50%) is approximately 1.4% in general population 1
• Predominantly affects the carotid bifurcation and proximal internal carotid artery
• Often presents with asymptomatic bruits or transient ischemic attacks

3. Renal Arteries

• Approximately 90% of renovascular stenotic lesions are due to atherosclerosis 1
• Most often affects the aorto-ostial segment (proximal 1 cm of main renal artery) 1
• Can lead to renovascular hypertension and renal insufficiency
• Prevalence increases with age (5.5-9.1% in elderly population) 1

4. Mesenteric Arteries

• Less common but potentially devastating when symptomatic
• Accounts for approximately 5% of intestinal ischemic events 1
• Superior mesenteric artery most commonly affected
• Can cause chronic mesenteric ischemia (abdominal angina)

5. Subclavian Arteries

• Prevalence of subclavian artery stenosis is approximately 1.9% in general population 1
• Increases with age from 1.4% in those <50 years to 2.7% in those >70 years
• Can cause subclavian steal syndrome and arm claudication

Common Biopsy Sites for Diagnosis

When atherosclerosis is suspected, the following sites are commonly biopsied to confirm diagnosis:

1. Temporal Artery

• Most frequently biopsied vessel for suspected vasculitis but can show atherosclerotic changes
• Relatively accessible and safe procedure
• Low complication rate

2. Skin/Subcutaneous Tissue

• Useful for diagnosing small vessel atherosclerosis
• Can reveal cholesterol emboli in dermal arterioles

3. Peripheral Arteries

• Segments obtained during revascularization procedures (endarterectomy specimens)
• Common sites include:
  • Carotid endarterectomy specimens
  • Femoral artery segments during bypass procedures
  • Amputated limbs in severe cases of peripheral artery disease

4. Renal Biopsy

• May reveal atherosclerotic nephropathy
• Performed when renovascular disease is suspected but imaging is inconclusive
• Shows characteristic arterial wall thickening and hyalinization

Pathological Features on Biopsy

Atherosclerotic lesions typically show:

• Intimal thickening with lipid accumulation
• Foam cell formation
• Fibrous cap development
• Calcification in advanced lesions
• Inflammatory cell infiltration
• Media hyalinization in small vessels 1

Clinical Considerations

• The pattern of atherosclerosis varies between vascular beds - carotid plaques are primarily lipid-rich, coronary plaques have more fibrotic components, and femoral plaques are predominantly fibrocalcific 2
• Atherosclerosis in one vascular bed increases the likelihood of disease in other territories 1
• Risk factors affect different vascular beds with varying intensity - diabetes has a stronger association with peripheral artery disease, while smoking affects all vascular territories 2

Pitfalls and Caveats

1. Sampling error: Atherosclerosis can be patchy, and a negative biopsy does not exclude the diagnosis
2. Procedural risks: Biopsy of major vessels carries risks of bleeding, thrombosis, and embolization
3. Diagnostic alternatives: Non-invasive imaging (duplex ultrasonography, CT angiography, MR angiography) is often preferred before considering biopsy 1
4. Incidental findings: Atherosclerotic changes are common in elderly patients and may not be the primary pathology

Remember that while biopsy can confirm atherosclerosis, the diagnosis is typically made through a combination of clinical presentation, risk factor assessment, and non-invasive imaging studies rather than through tissue sampling alone.